West Nile Studies Begin

The mysteries of West Nile virus are being uncovered at Colorado State University (CSU), thanks to a joint effort of the United States Equestrian Team (USET), the Centers for Disease Control (CDC), and the United States Department of Agriculture (USDA). West Nile virus, which is a type of encephalitis thought to be spread by the bite of an infected mosquito, appeared in a group of horses in Long Island, N.Y., in the autumn of last year. Studies were to begin immediately, pending approval of the CSU laboratory facility by the USDA.

Richard Bowen, DVM, PhD, associate professor of Biology at CSU, is coordinating the investigation into the virus, which caused the death of 13 out of 22 symptomatic horses. Previously, 39 human cases were confirmed in New York City, and six deaths were attributed to the disease.

“We need to establish a baseline of information by looking at what West Nile does in the horse, how virulent it is, and how much disease causes short- and long-term effects,” said Bowen. This gathering of information of how West Nile behaves in horses and amplified hosts is critical prior to making a vaccine or formulating any type of control strategy.

According to Bowen, nobody knows the likelihood that West Nile will show up again in the eastern United States during mosquito season. “If it establishes, that would accelerate efforts to test vaccines so there would be something for horse owners to use.”

The faculty researchers will be working with West Nile that has been isolated from a dead crow and a dead horse. Twelve equines will be used for the studies, which will be performed in a biocontainment laboratory. The CDC is providing mosquitos for administration of the virus to the study subjects.

Twice daily, researchers will assay for virus, and note how much is present and when clinical signs occur. Clinical signs of the disease are serious central nervous system disturbances.

A large network of professionals at CDC and the state veterinary office are watching the results and giving advice.

Bowen’s lab has been doing equine encephalitis research for a number of years. The group of researchers plans to disseminate its information in lay and professional journals. “As soon as we feel confident with the information (we’ve discovered), we will release it.”

The plans for study were the result of a conference in January that was sponsored by the USET and Stadium Jumping, Inc. in conjunction with the Florida State Veterinarian. Practitioners and officials of the horse industry shared the latest information on West Nile at that meeting. William J. Barnes, the owner of a prominent equine shipping agency based in Westfield, N.J., helped coordinate the conference. “My primary interest was as a horse owner. West Nile poses a threat of unknown severity,” said Barnes.

Europe, Hong Kong, and the United Arab Emirates placed a limited ban on the import of horses during the West Nile outbreak. Diseases such as these therefore have a major political and economic impact. All anecdotal field research suggests that the horse is a dead-end host of the virus, and this study hopefully will affirm this observance. “There are pockets of endemic West Nile in Europe,” said Barnes. “By establishing the risk, we can keep the gates open to Europe for competition.”

A free panel discussion was to convene on March 6 at the James A. Baker Institute for Animal Health at Cornell University.

Scheduled to appear on the panel were representatives from the Foreign Disease Lab at Plum Island, N.Y., officials from the USDA, N.Y. State Department of Agriculture, Cornell University, and John Andresen, DVM, the vet who treated 21 of the West Nile-affected horses.

About the Author

Stephanie L. Church, Editor-in-Chief

Stephanie L. Church, Editor-in-Chief, received a B.A. in Journalism and Equestrian Studies from Averett College in Danville, Virginia. A Pony Club and 4-H graduate, her background is in eventing, and she is schooling her recently retired Thoroughbred racehorse, Happy, toward a career in that discipline. She also enjoys traveling, photography, cycling, and cooking in her free time.

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